Why?
Are some "mature" videos showing up, or something?!?
I don't know of any way to restrict movies from popping up. Perhaps if you have another hard drive, you could put your "other" videos on that, and unmount the volume from within Disk Utility, thus making them unavailable.
That might work.
Or create a hidden folder - make a new folder named "other" or something like that. Then, launch the terminal, and type in " mv ~/other ~/.other. Then, to open the folder from the Finder, hit Apple+Shift+G, and type in ~/.other, and it will open the folder. Then, when you close that Finder window, the folder will disappear again.
That might work, too.